【作者】 杨强；

【导师】 刘忠；

【作者基本信息】 天津科技大学 ， 制浆造纸工程， 2004， 硕士

【摘要】 甲壳素在自然界中广泛存在，其存在量仅次于纤维素。因此，如何充分利用这一宝贵资源，具有重大的现实意义。壳聚糖是甲壳素脱乙酰基后的衍生物。目前，壳聚糖在造纸工业中有一定范围的应用，应用程度主要受其昂贵的价格所制约。因此，对壳聚糖进行改性是这一领域研究的热点。 本论文对下面内容进行了初步研究：从虾壳中提取壳聚糖；壳聚糖接枝丙烯酰胺，制备改性壳聚糖(简称CAM)：改性壳聚糖的应用和增强机理。 从虾壳中提取壳聚糖，分别研究了脱钙、脱蛋白质和脱乙酰基反应的各个影响因素，并对壳聚糖进行红外光谱分析。 根据自由基反应机理，采用氧化—还原引发体系，对壳聚糖和丙烯酰胺进行自由基接枝共聚反应，制备出CAM。分别研究了引发剂用量、反应温度、反应时间和单体浓度等因素对接枝共聚反应的接枝效率和接枝率的影响，并找出好的工艺条件：当过硫酸钾浓度为3mmol／L，亚硫酸氢钠浓度为1.5mmol／L，反应时间3小时，反应温度50℃，丙烯酰胺与壳聚糖的质量比为8。 将改性壳聚糖应用于不同的浆料，都有较好的增强效果。当用量为0.8％时，漂白麦草浆成纸的裂断长提高了910米，耐破指数提高了29.6％，当用量为0.2％时，成纸的撕裂指数提高了26.5％；当用量为0.8％时，漂白芦苇浆成纸的裂断长提高了23.9％；当用量为0.6％时，废报纸脱墨浆成纸的裂断长提高了20.3％；当用量为0.4％，纸板的环压指数提高了20.0％，裂断长提高了20.3％，耐破指数提高了7.69％，伸长率提高了28.2％。 从硅藻土絮凝实验可以看出，影响改性壳聚糖絮凝效果的因素有：w(AM)／w(Chitosan)、pH值、沉降时间和用量。将改性壳聚糖应用于造纸白水(今晚报)，有较好的絮凝效果。当改性壳聚糖的用量为5mg／L时，白水的浊度去除率为98.9％，COD去除率为75.8％；PAC和改性壳聚糖复配使用能够取得好的絮凝效果，100mg／LPAC+1.0mg／L改性壳聚糖能够取得和5.0mg／L改性壳聚糖相近的COD去除率和浊度去除率，从而可以通过复配来降低使用成本。 对改性壳聚糖的增强机理进行初步研究表明：改性壳聚糖能够提高天津科技大学硕士学位论文纸张纤维本身强度，并且能够增加纤维间的结合面积。更多还原

【Abstract】 Chitin is abundantly present in nature and its amount is only inferior to cellulose. So how to avail of it is of great importance to human being. The derivative of chitin called chitosan is mainly produced by alkaline N-deacetylation of chitin. Chitosan is poly [ -(1,4)-2-amino-2-deoxy-D-glucopyranose]. At present, due to its high market price, chitosan can only be applied in paper making industry to some extent. Thus, recent years, modification carried out onto chitosan is the hotspot in this field to extend its application.In this paper, the following aspects were primarily studied, including: the preparation of chitosan from shrimp shells; the preparation of graft copolymer of chitosan with acrylamide (CAM); the application and the mechanism of modified chitosan.When isolating chitosan from shrimp, the reactions of descalcium, desprotein and deacetyl were systematically studied under different conditions. The structures of chitosan were characterized by infrared spectrum (IR).According to free radical theory, the CAM was synthesized with acrylamide and chitosan, through oxidation-reduction initiator systems in acetic acid aqueous solution. In order to obtain the optimum technological conditions, the dosage of 鈥?initiators, temperature of reaction, time of reaction and concentration of monomer were studied. The higher grafting rate (%) and the higher efficiency of grafting (%) were obtained when the dosage of potassium persulfate was 3 mmol/L, the dosage of sodium bisulfite was 1.5 mmol/L, temperature of reaction at 50 , time of reaction is 3 hours, the rate of w(Am)/w(Chitosan) is 8.The modified chitosan was applied in bleaching wheat pulp, deinking pulp, bleaching reed pulp and paperboard. The results showed that the modified chitosan has better potential to be used as dry strength for paper. For bleaching wheat pulp, the breaking length and burst index of paper were respectively increased by 910m and 29.6% when the modified chitosan dosage was 0.8%; the tear index of paper was increased by 26.5% when the dosage was 0.2%. For bleaching reed pulp, the breaking length of paper was increased by 23.9% when the dosage was 0.8%. For deinking pulp, the breaking length of paper was increased by 20.3% when the dosage was 0.6%. For paperboard, the ring crush index of paper was increased by 20.0%, the breaking length increased by 20.3%, burst index increased by 7.69%, elongation rate increased by 28.2% when the dosage was 0.4%. On the other hand,the modified chitosan was applied in disposal of wastewater. The result showed the modified chitosan has better flocculation potential to the white water (from Jinwan newspaper factory) and tripoli. In order to examine how to the effect factors including w (Am)/w (Chitosan), pH, time of sedimentation, and dosage influence its flocculation ability, the modified chitosan was applied in tripoli. When the modified chitosan was applied in disposal of white water, 98.9% turbidity and 75.8%COD can be decreased by 5mg/L dosage of the flocculant. And the mixture of 1mg/L the modified chitosan and 100mg/L PAC has as exactly the same flocculation potential as 5mg/L modified chitosan to white water.In this experiment, the mechanism of modified chitosan as strength agent is preliminarily studied. The result showed that the modified chitosan can improve fiber strength to some extent and can increase the bonding area.更多还原